1. Field
The present disclosure relates to sensors with mechanical transducing capability. More particularly, the disclosure is directed to sensors having a piezoelectric transducer and an integrated preamplifier and a two-wire interface connected via a cable to a constant current or constant voltage power source for power input, and to a data acquisition circuit for signal output.
2. Description of the Prior Art
By way of background, piezoelectric transducers used for detection of vibrations and other dynamic physical parameters are often installed at locations that are remote from monitoring equipment that evaluates the sensor output. To overcome the noise and interference inherent in such environments, line drive piezoelectric sensors have been developed that combine a piezoelectric transducer and a built-in preamplifier that transforms the high impedance charge mode output of the transducer into a low impedance voltage or current output signal. A two-wire interface and associated two-wire cable (such as a coaxial cable) connects the sensor to a remote constant current or constant voltage power source for power input, and to a remote data acquisition circuit for signal output. The two-wire cable may be as long as several hundred meters. In some piezoelectric sensor designs, the sensor is powered by a constant current power source and the sensor's output is a modulated bias voltage signal. In other piezoelectric sensor designs, the sensor is powered by a constant voltage power source and the sensor's output is a modulated bias current signal.
Line drive piezoelectric sensors as described above are designed to measure only a single parameter, such as vibration. If an additional parameter needs to be measured, such as temperature in situations where both parameters are need to be monitored at the same measurement location, a separate sensor and lengthy cable connection to a remote unit are required. This redundancy adds design complexity and expense.
It is to improvements in line drive piezoelectric sensing technology that the present disclosure is directed. In particular, an integrated sensor is proposed that combines mechanical transducing with temperature monitoring.